The patch below does not apply to the 3.18-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 8a0d18c62121d3c554a83eb96e2752861d84d937 Mon Sep 17 00:00:00 2001
From: Bart Van Assche bart.vanassche@wdc.com Date: Wed, 11 Oct 2017 10:27:26 -0700 Subject: [PATCH] IB/srp: Avoid that a cable pull can trigger a kernel crash
This patch fixes the following kernel crash:
general protection fault: 0000 [#1] PREEMPT SMP Workqueue: ib_mad2 timeout_sends [ib_core] Call Trace: ib_sa_path_rec_callback+0x1c4/0x1d0 [ib_core] send_handler+0xb2/0xd0 [ib_core] timeout_sends+0x14d/0x220 [ib_core] process_one_work+0x200/0x630 worker_thread+0x4e/0x3b0 kthread+0x113/0x150
Fixes: commit aef9ec39c47f ("IB: Add SCSI RDMA Protocol (SRP) initiator") Signed-off-by: Bart Van Assche bart.vanassche@wdc.com Reviewed-by: Sagi Grimberg sagi@grimberg.me Cc: stable@vger.kernel.org Signed-off-by: Doug Ledford dledford@redhat.com
diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c index 778a08250f16..8ceb4bb011f1 100644 --- a/drivers/infiniband/ulp/srp/ib_srp.c +++ b/drivers/infiniband/ulp/srp/ib_srp.c @@ -665,12 +665,19 @@ static void srp_path_rec_completion(int status, static int srp_lookup_path(struct srp_rdma_ch *ch) { struct srp_target_port *target = ch->target; - int ret; + int ret = -ENODEV;
ch->path.numb_path = 1;
init_completion(&ch->done);
+ /* + * Avoid that the SCSI host can be removed by srp_remove_target() + * before srp_path_rec_completion() is called. + */ + if (!scsi_host_get(target->scsi_host)) + goto out; + ch->path_query_id = ib_sa_path_rec_get(&srp_sa_client, target->srp_host->srp_dev->dev, target->srp_host->port, @@ -684,18 +691,24 @@ static int srp_lookup_path(struct srp_rdma_ch *ch) GFP_KERNEL, srp_path_rec_completion, ch, &ch->path_query); - if (ch->path_query_id < 0) - return ch->path_query_id; + ret = ch->path_query_id; + if (ret < 0) + goto put;
ret = wait_for_completion_interruptible(&ch->done); if (ret < 0) - return ret; + goto put;
- if (ch->status < 0) + ret = ch->status; + if (ret < 0) shost_printk(KERN_WARNING, target->scsi_host, PFX "Path record query failed\n");
- return ch->status; +put: + scsi_host_put(target->scsi_host); + +out: + return ret; }
static int srp_send_req(struct srp_rdma_ch *ch, bool multich)